The present invention relates to ultrasonic transducers and, more particularly, to an ultrasonic transducer having acoustic elements with electrorheological fluid therein for dynamically focusing and steering a beam of ultrasonic energy.
Ultrasonic transducers for medical or industrial applications include one or more piezoelectric elements sandwiched between a pair of electrodes. The electrodes are connected to a voltage source, and when voltage is applied thereto, the piezoelectric element is excited at a frequency corresponding to that of the applied voltage. As a result, the piezoelectric element emits an ultrasonic beam into the media to which it is coupled at frequencies corresponding to the excitation pulse. Conversely, when an ultrasonic beam strikes the piezoelectric element, the element produces a corresponding voltage across its electrodes.
By selectively transmitting an ultrasonic beam and receiving echo signals therefrom, ultrasonic transducers can be used for non-destructive evaluation (NDE) of various materials in both medical and industrial applications. For example, ultrasonic transducers are used for ultrasonic pulse-echo inspection of metal objects or manufactured parts made of large grain metals such as titanium or the like, to identify flaws in the metal, abnormally large grains, or any other indications of interest.
Ultrasonic inspection systems must incorporate some scheme for focusing and directing sound radiation emitted from the transducer to provide spacial resolution. In order to thoroughly inspect an object it is necessary to focus and/or direct the beam of ultrasonic energy at various locations relative to the object being inspected. For example, it is desirable for an inspection system to be capable of focusing the sound beam at various depths within the object and/or to direct the sound beam to various locations on or within the object. In other words, ultrasonic inspection systems require a means for enabling an entire region of interest on an object to be scanned with the beam of ultrasonic energy. The region of interest may be a one-dimensional line on or through the object, a two-dimensional plane within the object, or a three-dimensional section of the object. Thus, ultrasonic inspection systems require sound beam control in all dimensions necessary to scan the object in accordance with the particular application and region of interest.